'''Chicago''' ( or ) is the List of United States cities by population|third most populous
city in the United States
. With over 2.7 million residents, it is the most populous city in the state of Illinois
and the Midwestern United States|Midwest
. The Chicago metropolitan area
, often referred to as Chicagoland
, has nearly 10 million people and is the List of metropolitan areas of the United States|third-largest
in the U.S.
Chicago is the county seat|seat
of Cook County, Illinois|Cook County
Chicago was incorporated as a city in 1837, near a Chicago Portage|portage
between the Great Lakes
and the Mississippi watershed|Mississippi River watershed
, and grew rapidly in the mid-nineteenth century.
The city is an international hub for finance, commerce, industry, technology, telecommunications, and transportation: O'Hare International Airport
is the World's...